Quenching of fluorescence from semiconducting SWNTs has been ascribed to their interactions with metallic SWNTs or bundles.(3, 8) Alternatively, weak fluorescence from SWNTs has been attributed to structural defects introduced during synthesis or processing,(24) hole doping of the SWNT sidewall via oxygen adsorption,(17) or direct protonation.(16) Structural defects are thought to generate trap states that open new nonradiative decay channels to photoexcited excitons via Auger recombination.(17) Further, the asymmetric line shape observed for individual SWNTs at low temperatures has been attributed to unintentional doping, which can occur during synthesis or processing.(4) Recent preparation of SWNTs in an oxygen-excluding surfactant led to an ensemble QY as high as 20% for SWNTs in an organic solvent,(10) although this value is still debated and the QY for SWNTs suspended in this surfactant in water remained low (∼1%).(10, 25)